The proposed experimental, simulation, and theoretical EEG/MEG studies will develop modern engineering tools for future use by cognitive and medical scientists who carry out physiological studies using steady-state visual evoked potentials (SSVEPs). SSVEP provides robust measures of neocortical dynamic and cognitive function that are largely artifact-free. These tools are potentially applicable to a wide variety of disease states, including mental disorders (ADHD, depression, schizophrenia, depression, sleep disorders, etc.) and neurological conditions (epilepsies, head trauma, strokes, coma, Alzheimer's disease, etc.). The proposed tools combine EEG with MEG and new paradigms and analytic methods to quantify dynamic (spatial-temporal) properties of SSVEPs. This framework will be used in experimental studies of localized and distributed brain networks in spatial and feature attention tasks. The experimental SSVEP data will be interpreted in the context of cell assembly formation embedded within a background of "synaptic action fields" using theoretical models of localized and distributed brain networks based on genuine physiology and anatomy. This theoretical construct provides the necessary connection between physiology and EEG/SSVEP data. The essential power of this method is that localized and distributed brain networks operate over different frequency ranges and thus can be easily investigated with SSVEPs. In this manner, a triple correspondence between SSVEP dynamics, cognitive processes, and theoretical models will be obtained. The EEG and SSVEP tools developed in these studies should provide firm foundations for the physiological interpretation of later studies applied to a wide range of specific cognitive or medical conditions. These tools will be freely distributed as software for high-resolution EEG, MEG, and SSVEP analysis, modeling and simulation with a supporting manual and examples. PUBLIC HEALTH RELEVANCE: EEG is a widely used research and diagnostic tool in a wide variety of disease states including mental disorders and neurological conditions. This project significantly advances EEG based neuroscience by developing new experimental methods for cognitive and clinical studies in conjunction with corresponding theoretical models of brain dynamics and physics of electromagnetic fields of the brain.